Research Article Salivary Interleukin-6 and C-Reactive Protein/Mean Platelet Volume Ratio in the Diagnosis of Late-Onset Neonatal Pneumonia Ahmed Omran , 1 Yasmin Ali, 1 Mohamed Osama Abdalla , 2 Sonya El-Sharkawy, 3 Ahmed R. Rezk , 4 and Abdelmoneim Khashana 1 1 Department of Pediatrics & Neonatology, Faculty of Medicine, Suez Canal University, Ismailia, Egypt 2 Department of Clinical Pathology, Faculty of Medicine, Suez Canal University, Ismailia, Egypt 3 Department of Pediatrics & Neonatology, Faculty of Medicine, Port Said University, Port Said, Egypt 4 Department of Pediatrics, Ain Shams University, Cairo, Egypt Correspondence should be addressed to Ahmed Omran; agomran1@yahoo.com Received 28 August 2021; Revised 26 September 2021; Accepted 27 September 2021; Published 18 October 2021 Academic Editor: Syed Sameer Aga Copyright © 2021 Ahmed Omran et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Neonatal pneumonia is a serious respiratory infectious disease with a high rate of case fatality in developing countries. Salivary cytokines could serve as interesting noninvasive markers in the diagnosis of neonatal pneumonia. The aim was to assess the diagnostic role of salivary and serum interleukin-6 (IL-6), C-reactive protein/mean platelet volume (CRP/MPV) ratio, and the combination of these markers in the diagnosis of late-onset neonatal pneumonia in full-term neonates. Seventy full-term neonates, 35 with late-onset neonatal pneumonia and 35 controls, were enrolled in this prospective case-control study. Complete blood count (CBC), salivary and serum IL-6, and CRP concentrations were measured for all the study subjects. The sensitivity, specificity, positive predictive value, and negative predictive value of salivary IL-6, serum IL-6, and CRP/MPV ratio for the diagnosis of late-onset neonatal pneumonia were determined. At the cutoff point of >34 pg/ml, salivary IL-6 showed 82.86% sensitivity and 91.43% specificity. CRP/MPV ratio showed a sensitivity of 97.14% and specificity of 85.71% at a cutoff value > 0:88. The combination of salivary IL-6 and CRP/MPV ratio improved the sensitivity and specificity to 100%. The current study shows for the first time that both salivary IL-6 and CRP/MPV ratio are suitable markers for the diagnosis of late-onset neonatal pneumonia in full-term neonates. 1. Introduction Neonatal pneumonia remains a major global health burden and contributes to annual deaths of nearly one million neo- nates that represent 10% of global child mortality [1]. Although diagnosis of neonatal pneumonia could be a chal- lenging task, accurate and very early diagnosis is essential for proper treatment and avoids complications. Interleukin-6 (IL-6) is a pleiotropic proinflammatory cytokine produced by a variety cells in response to infection [2]. Blood IL-6 is an early sensitive marker of neonatal bac- terial infection and one of the most studied cytokines in the diagnosis of infection in neonates [3–12]. In early stages of pneumonia, alveolar macrophages pro- duce proinflammatory cytokines. The main cytokines pro- duced are tumor necrosis factor-α and IL-6, and their systemic and bronchoalveolar levels increase subsequently during the disease course [13, 14]. Blood IL-6 is a useful marker in determining the severity of the lung injury and inflammatory response in children with pneumonia, with higher levels correlating with disease severity and early mor- tality [15–17]. Saliva represents an excellent noninvasive, easy to per- form, and patient-friendly biofluid for the screening of neo- natal infections [18–20]. Salivary analysis is a potentially novel tool for the diagnosis of pneumonia in children [21, Hindawi Journal of Immunology Research Volume 2021, Article ID 8495889, 7 pages https://doi.org/10.1155/2021/8495889